Amp popping noise when switching pickups

[g1]

They can both now be defective. There pre-testing may not screen for this particular defect, or they may have went bad since you got them. It's impossible to say, but I don't think something you did will have caused them to go bad. And it may not be so much as a defect, as just at the very low end of tolerance for this particular parameter.

[catalin gramada]

I not pretty sure but I can guess the mod you put in leaves the tube after the pot without any dc reference to the ground. If is true you have to put 1M resistor between input of this tube to the ground. Can put any value from ten k just to check if still popping. If works you have to instal 1M here.I talked about the input of the tube after the pot you did the mod .You should have a wire from the mod to a input of a tube. Just put a resistor from those tube input to the ground of those tube. Any value from few kohm works to test if you problem is solved. Replace with 1M if works. Cheers

[Amish Mel]

I not pretty sure but I can guess the mod you put in leaves the tube after the pot without any dc reference to the ground. If is true you have to put 1M resistor between input of this tube to the ground. Can put any value from ten k just to check if still popping. If works you have to instal 1M here.I talked about the input of the tube after the pot you did the mod .You should have a wire from the mod to a input of a tube. Just put a resistor from those tube input to the ground of those tube. Any value from few kohm works to test if you problem is solved. Replace with 1M if works. Cheers

Thanks, if these tubes develop the same symptoms I will look into that.

[catalin gramada]

[Mick Bailey]

I not pretty sure but I can guess the mod you put in leaves the tube after the pot without any dc reference to the ground.

The pot already acts as the ground reference.

[catalin gramada]

That.s true in posted schematic. But as I understand a sort of mod was interposed between pot and input.so if some capacitors was interposed between wiper and tube you can say good bye to any reference to ground and need to instal a resistor here.as big as better.1-2M to keep input impedance as large posible .but any value will work for a test. There are just mine suposition. I don.t know how the mod looks like and how it was instaled but from a simptoms description it is a posibility to be right. It takes 2 min to check.